The invention relates to an arrangement for protecting a cooling system of an internal combustion engine from excess pressure.
Such an arrangement is known from the European Patent Application 0 177 860 in which a coolant container is protected from excess pressure by means of a two-stage valve arrangement inserted in a filler mouthpiece. Ahead of the first valve there is provided a float, which disables the first valve in the case of an excessive rise of the cooling water level. Pressure balancing can therefore be achieved only by way of the second valve which is designed to open at a higher pressure than the first valve. It is also proposed that a throttle opening should be provided between the highest point in the coolant container and the region in front of the first valve to ventilate the gas volume enclosed in the coolant container.
This arrangement has the disadvantage that there is no reliable protection against overfilling when topping up with coolant. Although the inlet cross-section is reduced from a certain fill level by the raising of the float, the arrangement does not prevent further slow filling. In addition, the air contained in the coolant container can escape via the throttling opening so that no air buffer volume, which could act as a protection against excessive filling, can form.
A cooling water balance container with a simple arrangement for protecting against overfilling is known from the German Patent Specification 41 07 183, in which an excess pressure valve, which is closed during filling, is arranged in a ventilation conduit.
The object of the invention is to provide an arrangement for protecting a cooling system of an internal combustion engine from excess pressure in a simple manner in such a way that, on the one hand, excess pressure protection is insured for the complete gas and fluid volume enclosed in the cooling system in all operating ranges and, on the other hand, overfilling of the coolant container is safely prevented.